Abstract: Heavy metal ions in water are harmful to human body, especially Pb(Ⅱ) and Hg(Ⅱ) ions, therefore, it is necessary to remove Pb(Ⅱ) and Hg(Ⅱ) ions. By adjusting the amount of concentrated hydrochloric acid used in the synthesis process, defective mercapto-functionalized zirconium-based metal-organic frameworks (Zr-MOFs) UiO-66-(SH)₂ were synthesized and used for the removal of Pb(Ⅱ) and Hg(Ⅱ) ions from their aqueous solutions. Through adsorption experiments of the heavy metal ions, it is found that UiO-66-(SH)₂ showed more defects when more hydrochloric acid was introduced in its synthesis, and enhanced adsorption capacity for Pb(Ⅱ) and Hg(Ⅱ) ions. The defective UiO-66-(SH)₂ exhibited maximum adsorption capacities of 45.11 and 258.75 mg/g for low-concentration Pb(Ⅱ) and Hg(Ⅱ) ions (50-70 mg/L) with high adsorption selectivity over many other ions, respectively. After three adsorption-desorption cycles, no obvious decrease in the adsorption capacity of the defective UiO-66-(SH)₂ for Pb(Ⅱ) and Hg(Ⅱ) ions was observed, indicating a high potential of this material in the removal of heavy metal ions from water.